A conventional solid state imaging device has a plurality of photodiodes formed on a semiconductor substrate, and a plurality of microlenses respectively formed on the photodiodes. The photodiodes and the microlenses constitute pixels.
A conventional method for manufacturing a solid state imaging device is as follows. First, a lens material is uniformly applied on photodiodes. Next, the lens material is exposed and developed to form block-shaped lens bodies every other pixel. Next, the block-shaped lens bodies are melted by heat to be formed in a semispherical shape. The semispherical lens bodies are then cooled and cured, thereby forming first microlenses. Second microlenses are then similarly formed so as to fill a space between the first microlenses.
In the conventional method for manufacturing a solid state imaging device, no gap is formed between the first microlens and the second microlens, and the first and second microlenses are formed in a semispherical shape having a desired curvature. Thus, a solid state imaging device is manufactured, which has a plurality of microlenses having a contiguous spherical shape and has high sensitivity.
However, conventionally, it is necessary to repeat a step of forming microlenses twice in order to form the solid state imaging device having high sensitivity. Therefore, the conventional method for manufacturing a solid state imaging device disadvantageously has a long manufacturing time.
Furthermore, the above-mentioned manufacturing method requires a photomask for forming block-shaped lens bodies for the first microlenses and a photomask for forming block-shaped lens bodies for the second microlenses. Therefore, a cost required to manufacture the solid state imaging device also has increased.